Iris diaphragm



May 12, 1964 MAHN IRIS DIAPHRAGM Filed Feb. 6, 1961 m m m y Herbert Mahn United States Patent O IRIS DIAPHRAGM Herbert Mahn, Bad Kreuznach, Germany, assignor to Jos. Schneider & Co., Optische Werke, Bad Kreuznach, Germany, a corporation of Germany Filed Feb. 6, 1961, Ser. No. 87,437 Claims priority, application Germany May 5, 1960 6 Claims. (Cl. 95-64) I My present invention relates to an iris diaphragm, of the general type used for photographic or cinematographic objectives, in which a plurality of iris leaves are swingable about respective pivots disposed along the periphery of a circle whereby the suitably curved inner edges of these leaves together define an opening of adjustable size concentric with that circle.

It is known to mount the iris leaves of such diaphragms between two relatively rotatable coaxial rings, one of these rings supporting their respective pivots while the other is provided with radially, obliquely or helicoidally extending slots or grooves for the guidance of pins which control the swing of the leaves about their pivots. With diaphragms of small dimensions it is sometimes difiicult to accommodate the necessary number of grooves or slots on one ring without introducing an unfavorably large pitch or camming angle which impedes the displacement of the leaves.

It is, therefore, an object of my present invention to provide an improved iris diaphragm of this general type in which these difiiculties are avoided and which, therefore, may be manufactured even in compact sizes by relatively cheap mass-production processes (e.g. stamping), by virtue of a crowding of the slots or grooves which therefore can be executed with less precision.

The invention realizes the foregoing object by providing the pivots of the swingable leaves alternately on one and the other of the two relatively rotatable, preferably identical rings, each of these rings being also provided with eamming formations (i.e. slots or grooves) engageable by the guiding elements or pins of the leaves pivoted to the respective other ring.

The invention will become more fully apparent from the following detailed description, reference being made to the accompanying drawing in which:

FIG. 1 is a front view of one of two rings forming part of a diaphragm embodying the invention;

FIGS. 2 and 3 are a front view and a rear view, respectively of the ring shown in FIG. 1 and of an identical second ring co-operating therewith, together with associated iris leaves;

FIG. 4 is a front view of the entire diaphragm assembled from the components shown in FIGS. 2 and 3; and

FIG. 4a is a cross-sectional view of the diaphragm along the plane denoted by line lVa-IVa in FIG. 4.

The diaphragm shown in the drawing comprises a pair of coaxially mounted, coextensive rings 1, 1 having radially projecting lugs 1a, 1a to facilitate their relative rotation. Ring 1 has a pair of diametrically opposite bores 2 for the pivots 6 of two iris leaves 5 and is also formed with a pair of diametrically opposite slots 3 for the guiding studs 4 of another pair of iris leaves 5'. The latter leaves have their pivot pins 6 received in diametrically opposite bores of ring 1' which in turn is formed with slots 3' to receive the guiding studs 4 of the leaves 5.

When the elements described above are assembled in the manner illustrated in FIG. 4, relative rotation of the rings 1 and 1' by their lugs 1a and 1a will cause the inner concave edges of the two leave pairs 5 and 5' to define a variable diaphragm aperture 7.

It will be apparent that, since the number of pivots and the number of guiding grooves or slots to be accommodated by each mounting ring is only half the total number exceed the two pairs illustrated in the 3,132,576 Patented May 12, 1964 .Z of iris leaves, their location on these rings will not constitute a major problem if the number of leaves should specifiic embodiment shown in the drawing. I

My invention is, of course, not limited to the particular configuration herein disclosed, but may be realized in various modificationswithout departing from the spirit and scope of the appended claims.

I claim: a I I 1. An iris diaphragm comprising a pair of relatively rotatable coaxial rings, a first set of iris leaves pivotally secured to one of said rings, a second set of iris leaves pivotally secured to the other of said rings, said one of said rings being provided with camming formations for the guidance of said second set of leaves, said other of said rings being provided with camming formations for the guidance of said first set of leaves, and guide means on each of said leaves remote from the pivot thereof and engaged by a respective camming formation whereby said leaves are swingable by relative rotation of said rings for defining a variable diaphragm aperture.

2. An iris diaphragm comprising a pair of relatively rotatable and substantially identical coaxial rings, a first set of iris leaves pivotally secured to one of said rings, a second set of iris leaves pivotally secured to the other of said rings, said one of said rings being provided with camming formations for the guidance of said second set of leaves, said other of said rings being provided with .camming formations for the guidance of said first set of leaves, and a projecting stud on each of said leaves remote from the pivot thereof and engaged by a respective camming formation whereby said leaves are swingable by relative rotation of said rings for defining a variable diaphragm aperture.

3. An iris diaphragm comprising a first and a second ring mounted for relative rotation about a common axis, and an even number of iris leaves respectively divided into two equal groups, the leaves of each group being pivotally secured to a respective one of said rings with freedom of swinging motion relative thereto, each of said rings being provided with a number of camming formations equaling half the number of said leaves, the leaves secured to each ring being provided with guide means remote from their pivots and engaging a corresponding camming formation on the opposite ring whereby said leaves are swingable by relative rotation of said rings for defining a variable diaphragm aperture.

4. An iris diaphragm comprising a first and a second ring mounted for relative rotation about a common axis, said rings being of substantially identical configuration, and an even number of iris leaves divided into two equal groups, the leaves of each group being pivotally secured to a respective one of said rings with freedom of swinging motion relative thereto, each of said rings being provided with a number of camming formations equaling half the number of said leaves, the leaves secured to each ring being provided with a projecting stud remote from its pivot and engaging a corresponding camming formation on the opposite ring whereby said leaves are swingable by relative rotation of said rings for defining a variable diaphragm aperture.

5. An iris diaphragm comprising a first and a second ring mounted for relative rotation about a common axis, and two pairs of iris leaves, the leaves of each pair being pivotally secured to a respective one of said rings at diametrically opposite locations with freedom of swinging motion relative thereto, the pivots of one pair being angularly offset from those of the other pair each of said rings being provided with a number of camming formations equaling half the number of said leaves, the leaves secured to each ring being each provided with guide means remote from its pivot and engaging a corresponding camming formation on the opposite ring whereby said leaves are swingable by relative rotation of said rings for defining a variable diaphragm aperture. 7

6. An iris diaphragm comprising a first and a second ring mounted for relative rotation about a common axis, said rings being of substantially identical configuration, and two pairs of iris leaves, the leaves of each pair being pivotally secured to a respective one of said rings at diametrically opposite locations with freedom of swinging motion relative thereto, the pivots of one pair being angularly offset from those of the other pair, each of said rings being provided with a number of cammingformations equaling half the number of said leaves, the leaves secured References Cited in the file of this patent UNITED STATES PATENTS 2,129,562 Brueck Sept. 6, 1938 FOREIGN PATENTS 27,433 Great Britain Dec. 17, 1908 

1. AN IRIS DIAPHRAGM COMPRISING A PAIR OF RELATIVELY ROTATABLE COAXIAL RINGS, A FIRST SET OF IRIS LEAVES PIVOTALLY SECURED TO ONE OF SAID RINGS, A SECOND SET OF IRIS LEAVES PIVOTALLY SECURED TO THE OTHER OF SAID RINGS, SAID ONE OF SAID RINGS BEING PROVIDED WITH CAMMING FORMATIONS FOR THE GUIDANCE OF SAID SECOND SET OF LEAVES, SAID OTHER OF SAID RINGS BEING PROVIDED WITH CAMMING FORMATIONS FOR THE GUIDANCE OF SAID FIRST SET OF LEAVES, AND GUIDE MEANS ON EACH OF SAID LEAVES REMOTE FROM THE PIVOT THEREOF AND ENGAGED BY A RESPECTIVE CAMMING FORMATION WHEREBY SAID LEAVES ARE SWINGABLE BY RELATIVE ROTATION OF SAID RINGS FOR DEFINING A VARIABLE DIAPHRAGM APERTURE. 